It is well known to use a combination spring and friction type vibration damper in a conventional vehicle clutch ahead of a manually operated transmission for the purpose of neutralizing any torsional vibrations emanating from the vehicle engine which would otherwise cause undesirable characteristics, e.g., impact loads, pulsations, noises, etc., in the transmission and driveline during operation of the vehicle.
With an automatic transmission having a constant slipping device, such as a fluid coupling or a hydraulic torque converter, the torsional vibrations in the system are efficiently absorbed hydraulically and a vibration damper has been found unnecessary. However, in order to enhance the fuel economy of an automotive vehicle equipped with an automatic transmission, a lock-up clutch may be incorporated into the fluid coupling or torque converter assembly which, at a predetermined point that may relate to vehicle speed, load, and acceleration, locks up the coupling or torque converter so that slippage does not occur and direct drive results. The lock-up action usually occurs after the automatic transmission has shifted into high gear.
Thus, when locked in direct drive, there is no opportunity for torsional vibrations from the engine to be absorbed hydraulically, and these vibrations tend to manifest themselves in a disturbing manner; the vibrations necessitating a damper assembly in the lock-up clutch device to eliminate the disturbance. Another problem of presently known vibration dampers is that the assembly will only allow a relatively small deflection amplitude. The present invention relates to a vibration damper assembly which will obviate the problems of small deflection amplitude.
The present invention relates to an improved vibration damper assembly which provides for a relatively low rate, high amplitude deflection between the driving and driven members. The assembly includes a hub operatively connected to the driven shaft and having two or more radial arms, a driving plate having at least two driving members, and at least one floating carrier journalled on the hub. Damping springs are positioned between the driving members and the floating carriers to provide an extended arc damping action.
The present invention also comprehends the provision of an improved vibration damper assembly which, in order to suppress torsional vibrations of various natures, permits an almost infinite number of performance curves using various spring combinations. The hub is provided with radially extending arms and each floating carrier is likewise provided with one or more radially extending arms. The arms of these members are circumferentially equally spaced in the inoperative condition by springs positioned between the arms. The hub arms are provided with slots to receive corresponding driving members secured to the driving plate so that the driving members are in axial alignment with the hub arms. The springs are divided into two or more groups operating in parallel with multiple springs of the same or various rates within each group operating in series through the use of the floating carriers.
The present invention further comprehends the provision of an improved vibration damper assembly providing variations in the damper action due to various spring combinations and unique spring deflection limiting members. The arm or arms of each floating carrier and the hub are provided at the outer ends with circumferential lips serving to retain the damper springs with spring deflection limiting members provided in one or more concentric spring sets. As the springs may vary in their rates, the application of torque will cause the lower rate springs to be compressed the most and, simultaneously, the higher rate springs to be compressed the least. When the spring deflection limiting members contact the floating carriers, the spring set or sets containing the limiting members will cease to be further compressed.
Another object of the present invention is the provision of an improved vibration damper assembly that will be equally useful in a torsional coupling between two shafts, a vehicle clutch for a manual transmission, or in a lock-up clutch associated with a hydraulic torque converter.
Further objects are to provide a construction of maximum simplicity, efficiency, economy and ease of assembly and operation, and such further objects, advantages and capabilities as will later more fully appear and are inherently possessed thereby.